Film-Tech Forum ARCHIVE: 'Gravity' only has sound in bypass...

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Posted by Buck Wilson (Member # 5885) on 11-28-2013, 10:27 PM:

Is this normal for a trashed print? I've never experienced it and to be completely honest I do not fully understand what bypass does.

That said, this print has no sound or very little/drops out if played 'regularly', that is, regular analog, no Dolby digital or anything. With bypass enabled, it sounds fine. In multiple houses. Why?

The first house we had it in, it would even kick around the inputs on the processor. Bizzare....

Again I will note, this print of Gravity is in AWFUL shape, but I've played prints in as bad or worse condition that had no such issue.

Posted by Mike Blakesley (Member # 26) on 11-28-2013, 11:28 PM:

Maybe the print was run with the sprockets "denting" the Dolby soundtrack area. (Assuming your problem is in Dolby Digital...?) Or that area was severely scratched.

Posted by Buck Wilson (Member # 5885) on 11-29-2013, 01:54 AM:

Sorry for the confusuon, we run analog all the time. We dont have Dolby digital. But Gravity doesnt have sound pretty much at all unless its in bypass, then its fine

Posted by Marcel Birgelen (Member # 6801) on 11-29-2013, 05:54 AM:

Maybe you could clarify what sound processors you're using?

Posted by Gordon McLeod (Member # 33) on 11-29-2013, 07:35 AM:

If you have sound only in bypass it indicates that probably something in the processor has died

Posted by Jock Blakley (Member # 6552) on 11-29-2013, 08:51 AM:

Considering that switching to bypass fixes the problem, I'd be looking at what happens in bypass.

You haven't mentioned what processors you use, but for arguments sake this is from the CP55 Operator's Manual:

quote:
The following occurs when the CP55 is in bypass mode:

- The front-panel fader remains operational but remote faders will not work.

- You cannot select among formats (...)

- Even when a stereo print is playing, a mono signal is fed to the screen speakers. Thus you can switch to bypass to keep the show going if one of the power amplifiers fails.

- The Dolby noise-reduction circuitry, 2:4 channel decoder, screen speaker equalisers, optional surround equaliser, and optional optical bass extension are not powered and thus do not operate.

So it would probably be a fault in one of the items listed in the last para... except that you say it's happening in more than one auditorium.

It can't be the print, since bypass changes nothing about the print and how its soundtrack is read.

Have you been able to try the affected houses with other prints or known material (even trailers)? Also, is your non-sync input working and sounding normal?

Posted by Buck Wilson (Member # 5885) on 11-30-2013, 12:56 AM:

This issue follows the print. That's why I'm so beyond baffled. One was a Ultra Stereo processor(sorry don't know the model offhand) and the current house it is in has a CP500.

Both houses have/do play anything but THIS print of Gravity just 'fine'.

Non sync in the ultra stereo house works fine, not currently hooked up in the cp500 house.

I swear, this place blows my mind literally every single day. The entire building is a fucking enigma. Nothing makes sense. Nothing.

And again I repeat, both houses play just 'fine' out of bypass, EXCEPT with this print of Gravity. I just don't understand.

It really doesn't matter, I'm just morbidly curious

Posted by Louis Bornwasser (Member # 3063) on 11-30-2013, 09:44 AM:

Is it possible that the print was recorded "out of phase?" If so, reversing ONEchannel on the Ultra stereo input would cure the problem. Remember all stereo films are largely MONO since dialog and some effects are in center. Therefore it would seem like there is no sound. If out-of-phase, you would mostly be hearing the surround channel; center would then be in your surround speakers. Louis

Other than that, there is nothing you can do to fix it.

Posted by Marcel Birgelen (Member # 6801) on 11-30-2013, 08:21 PM:

But if one of the two optical tracks would be out of phase, wouldn't the problem still persist in bypass mode or even be worse?

Interestingly, Gravity is one of the few movies until now, that put a lot of essential sound effects, music and even dialog in the surround channels, at least in the digital version of the mixes. I don't know if the SR mix retains that, by putting dialog and essential sound effects in the surround channel.

Posted by Phillip Grace (Member # 2262) on 12-01-2013, 01:16 AM:

Supposing the system gain in bypass is set higher than the main system gain, and you can only hear the sound at all for that reason. I guess that being a new film, the print has or should have a cyan dye sound-track. It might be worth comparing the colour of the track against the spectral sensitivity of the sound readers. What type of sound pick-ups are fitted to the projectors? White light? Or I.R? Is the track some wierd colour? How badly is the track itself damaged? Severe damage to one side of an analogue track will give the matrix decoder a really hard time. Does it play through the main system in Mono mode?
Once upon a time I had a print with a High Magenta soundtrack which had not been redeveloped properly. Volume dropped to near zero in the patches that the redeveloper missed.

Posted by Buck Wilson (Member # 5885) on 12-03-2013, 01:36 PM:

Track looks good, haven't looked at ti too deeply though. I've ran more damaged film without issue. Cyan track, red readers.

Haven't tried mono, I'll try that for giggles n grins